[Predictive factors of conservative breast surgery after neoadjuvant chemotherapy for breast cancer]

OBJECTIVES

The aim of our study was to evaluate the existence of predictive factors of conservative breast surgery after neoadjuvant chemotherapy (NAC) for breast cancer.

METHODS

We included all women with invasive breast cancer who received NAC and underwent breast surgery between January 2007 and December 2013 in our institution. Univariable and multivariable analyses were performed to determine the association between clinical and histological factors and conservative breast surgery.

RESULTS

During the study period, 229 women were included of whom 73 had breast conservative surgery (32%). At univariable analysis, significant predictive factors were age (OR 0.97 [CI 95% 0.95-0.99], P=0.02), radiological size (OR 0.97 [CI 95% 0.96-0.99], P<0.001), multifocality (OR 0.53 [CI 95% 0.27-1.05], P=0.06), breast inflammation (OR 0.15 [CI 95% 0.07-0.32], P<0.001) and the type of hormone receptors (P=0.12). In multivariable analysis, all these factors but age were significant factors and thus considered as independent predictive factors.

CONCLUSION

This work permitted to identify independent predictive factors of breast conservative surgery after NAC for breast cancer that will be included in a risk scoring system that we aim to evaluate prospectively.

A novel resorbable embolization microsphere for transient uterine artery occlusion: a comparative study with trisacryl-gelatin microspheres in the sheep model

PURPOSE

To evaluate angiographic recanalization, inflammatory reaction, and uterine damage after sheep uterine artery embolization (UAE) with a novel calibrated resorbable embolization microsphere (REM) and compare the results with control nonresorbable microspheres.

MATERIALS AND METHODS

Six hormonally artificially cycled sheep underwent bilateral UAE until stasis with either REM or trisacryl-gelatin microspheres (TGMS). At 7 days, control angiograms were obtained to assess the residual vascularization at arterial and parenchymal phases. The animals were then sacrificed for analysis of the presence of microspheres, inflammatory foreign body reaction, and surface areas of uterine damage.

RESULTS

Mean volume of microspheres injected per uterine artery (UA) or per animal did not differ between groups. At day 7, the flow was normal for six of six UAs that received embolization with REM versus only three of six UAs with TGMS (P = .0455, χ(2) test). Uterine parenchymography showed no defects in six UAs in the REM group versus five defects in six UAs in the TGMS group (P = .0060, χ(2) test). No REM or residual fragments of microspheres were observed on histologic analysis. TGMS were observed in tissues and accompanied by a mild inflammatory response. Necrosis rates were not significantly different between the two products, either in endometrium (REM 23.5% ± 28.8% [median 8.1%] vs TGMS 21.8% ± 23.7% [median 14.6%]) or in myometrium (REM 8.2% ± 22.7% [median 0.0%] vs TGMS 8.8% ± 20.8% [median 0.9%]). Endometrium alteration rate was lower with REM than with TGMS (39.7% ± 25.7% [median 34%] vs 60.6% ± 27.1% [median 71%]; P = .0060, Mann-Whitney test). Myometrium alteration rates were not significantly different between REM (45.7% ± 37.1% [median 63.0%]) and TGMS (37.8% ± 34.0% [median 19.1%]).

CONCLUSIONS

At 1 week after sheep UAE with REM, the recanalization was complete, the microspheres were completely degraded, and there was no remnant inflammatory response.

Biomineralization of Schlumbergerella floresiana, a significant carbonate-producing benthic foraminifer

Most foraminifera that produce a shell are efficient biomineralizers. We analyzed the calcitic shell of the large tropical benthic foraminifer Schlumbergerella floresiana. We found a suite of macromolecules containing many charged and polar amino acids and glycine that are also abundant in biomineralization proteins of other phyla. As neither genomic nor transcriptomic data are available for foraminiferal biomineralization yet, de novo-generated sequences, obtained from organic matrices submitted to ms blast database search, led to the characterization of 156 peptides. Very few homologous proteins were matched in the proteomic database, implying that the peptides are derived from unknown proteins present in the foraminiferal organic matrices. The amino acid distribution of these peptides was queried against the uniprot database and the mollusk uniprot database for comparison. The mollusks compose a well-studied phylum that yield a large variety of biomineralization proteins. These results showed that proteins extracted from S. floresiana shells contained sequences enriched with glycine, alanine, and proline, making a set of residues that provided a signature unique to foraminifera. Three of the de novo peptides exhibited sequence similarities to peptides found in proteins such as pre-collagen-P and a group of P-type ATPases including a calcium-transporting ATPase. Surprisingly, the peptide that was most similar to the collagen-like protein was a glycine-rich peptide reported from the test and spine proteome of sea urchin. The molecules, identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry analyses, included acid-soluble N-glycoproteins with its sugar moieties represented by high-mannose-type glycans and carbohydrates. Describing the nature of the proteins, and associated molecules in the skeletal structure of living foraminifera, can elucidate the biomineralization mechanisms of these major carbonate producers in marine ecosystems. As fossil foraminifera provide important paleoenvironmental and paleoclimatic information, a better understanding of biomineralization in these organisms will have far-reaching impacts.

Poly(ethylene glycol) methacrylate hydrolyzable microspheres for transient vascular embolization

Poly(ethylene glycol) methacrylate (PEGMA) hydrolyzable microspheres intended for biomedical applications were readily prepared from poly(lactide-co-glycolide) (PLGA)-poly(ethylene glycol) (PEG)-PLGA crosslinker and PEGMA as a monomer using a suspension polymerization process. Additional co-monomers, methacrylic acid and 2-methylene-1,3-dioxepane (MDO), were incorporated into the initial formulation to improve the properties of the microspheres. All synthesized microspheres were spherical in shape, calibrated in the 300-500 μm range, swelled in phosphate-buffered saline (PBS) and easily injectable through a microcatheter. Hydrolytic degradation experiments performed in PBS at 37 °C showed that all of the formulations tested were totally degraded in less than 2 days. The resulting degradation products were a mixture of low-molecular-weight compounds (PEG, lactic and glycolic acids) and water-soluble polymethacrylate chains having molecular weights below the threshold for renal filtration of 50 kg mol(-1) for the microspheres containing MDO. Both the microspheres and the degradation products were determined to exhibit minimal cytotoxicity against L929 fibroblasts. Additionally, in vivo implantation in a subcutaneous rabbit model supported the in vitro results of a rapid degradation rate of microspheres and provided only a mild and transient inflammatory reaction comparable to that of the control group.

Soil calcium availability influences shell ecophenotype formation in the sub-antarctic land snail, Notodiscus hookeri

Ecophenotypes reflect local matches between organisms and their environment, and show plasticity across generations in response to current living conditions. Plastic responses in shell morphology and shell growth have been widely studied in gastropods and are often related to environmental calcium availability, which influences shell biomineralisation. To date, all of these studies have overlooked micro-scale structure of the shell, in addition to how it is related to species responses in the context of environmental pressure. This study is the first to demonstrate that environmental factors induce a bi-modal variation in the shell micro-scale structure of a land gastropod. Notodiscus hookeri is the only native land snail present in the Crozet Archipelago (sub-Antarctic region). The adults have evolved into two ecophenotypes, which are referred to here as MS (mineral shell) and OS (organic shell). The MS-ecophenotype is characterised by a thick mineralised shell. It is primarily distributed along the coastline, and could be associated to the presence of exchangeable calcium in the clay minerals of the soils. The Os-ecophenotype is characterised by a thin organic shell. It is primarily distributed at high altitudes in the mesic and xeric fell-fields in soils with large particles that lack clay and exchangeable calcium. Snails of the Os-ecophenotype are characterised by thinner and larger shell sizes compared to snails of the MS-ecophenotype, indicating a trade-off between mineral thickness and shell size. This pattern increased along a temporal scale; whereby, older adult snails were more clearly separated into two clusters compared to the younger adult snails. The prevalence of glycine-rich proteins in the organic shell layer of N. hookeri, along with the absence of chitin, differs to the organic scaffolds of molluscan biominerals. The present study provides new insights for testing the adaptive value of phenotypic plasticity in response to spatial and temporal environmental variations.

In vitro evaluation of S-(+)-ibuprofen as drug candidate for intra-articular drug delivery system

Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the efficacy of S-(+)-ibuprofen on cartilage degradation as drug candidate for DDS loading. Humeral cartilage and joint capsule explants were collected from healthy sheep shoulder joints and they were cultured in mono- or in co-culture for 13 days with LPS in combination with S-(+)-ibuprofen at 50 µM and 1 mM. S-(+)-ibuprofen (50 µM) blocked prostaglandins production in LPS-activated explants but did not reduce cartilage degradation. By contrast, 1 mM S-(+)-ibuprofen treatment of cartilage explants reduced nitric oxide synthesis by 51% (p = 0.0072), proteoglycans degradation by 35% (p = 0.0114) and expression of serum amyloid protein - the main protein induced upon LPS challenge - by 44% (p < 0.0001). On contrary, in presence of synovial membrane, the protective effects of S-(+)-ibuprofen on cartilage damages were significantly diminished. At 1mM, S-(+)-ibuprofen reduced the cell lysis during culture of cartilage and joint capsule either in mono- or in co-culture. This study performed on sheep explants shows that 1 mM S-(+)-ibuprofen inhibited cartilage degradation via a mechanism independent of cyclooxygenase inhibition. Reduction of prostaglandins synthesis at 50 µM in all treatment groups and reduction of cartilage degradation observed at 1 mM suggest that S-(+)-ibuprofen could be considered as a promising drug candidate for the loading of intra-articular DDS.

What is the difference in organic matrix of aragonite vs. vaterite polymorph in natural shell and pearl? Study of the pearl-forming freshwater bivalve mollusc Hyriopsis cumingii

Aragonite pearl, vaterite pearl and shell nacre of the freshwater mollusc Hyriopsis cumingii (Zhejiang province, China) were chosen to analyze microstructure and organic composition in the different habits of calcium carbonate. SEM and TEM were used to reveal the microstructure and mineralogical phase. We found that tablets in vaterite exhibited more irregular texture and were packaged with more organic matrices than in aragonite forms. Then a peculiar method was introduced to extract water soluble matrix (WSM), acid soluble matrix (ASM) and acid insoluble matrix (AIM) from the three samples, and biochemical analysis of these organic matrixes involved in crystal formation and polymorph selection was carried out. High performance liquid chromatography (HPLC) confirms the hydrophobic pattern of the organic matrix intermingled with mineral, the opposite of the early mobilizable water soluble fraction. Amino acid composition confirms hydrophobic residues as major components of all the extracts, but it reveals an imbalance in acidic residues rates in WSM vs. ASM and in aragonite vs. vaterite. Electrophoresis gives evidence for signatures in proteins with a 140 kDa material specific for aragonite in WSM. Conversely all ASM extracts reveal the presence of about 55 kDa components, including a discrete band in vaterite extract.

Proteomic strategy for identifying mollusc shell proteins using mild chemical degradation and trypsin digestion of insoluble organic shell matrix: a pilot study on Haliotis tuberculata

A successful strategy for the identification of shell proteins is based on proteomic analyses where soluble and insoluble fractions isolated from organic shell matrix are digested with trypsin with the aim of generating peptides, which are used to identify novel shell proteins contained in databases. However, using trypsin as a sole degradative agent is limited by the enzyme's cleavage specificity and is dependent upon the occurrence of lysine and arginine in the shell protein sequence. To bypass this limitation, we investigated the ability of trifluoroacetic acid (TFA), a low-specificity chemical degradative agent, to generate clusters of analyzable peptides from organic shell matrix, suitable for database annotation. Acetic acid-insoluble fractions from Haliotis tuberculata shell were processed by trypsin followed by TFA digestion. The hydrolysates were used to annotate an expressed sequence tag library constructed from the mantle tissue of Haliotis asinina, a tropical abalone species. The characterization of sequences with repeat motifs featured in some of the shell matrix proteins benefited from TFA-induced serial cutting, which can result in peptide ladder series. Using the degradative specificities of TFA and trypsin, we were able to identify five novel shell proteins. This pilot study indicates that a mild chemical digestion of organic shell matrix combined with trypsin generates peptides suitable for proteomic analysis for better characterization of mollusc shell matrix proteins.

Coupling proteomics and transcriptomics for the identification of novel and variant forms of mollusk shell proteins: a study with P. margaritifera

Shell matrix proteins from Pinctada margaritifera were characterized by combining proteomics analysis of shell organic extracts and transcript sequences, both obtained from the shell-forming cell by using the suppression subtractive hybridization method (SSH) and from an expressed sequence tag (EST) database available from Pinctada maxima mantle tissue. Some of the identified proteins were homologues to proteins reported in other mollusk shells, namely lysine-rich matrix proteins (KRMPs), shematrins and molluscan prismatic and nacreous layer 88 kDa (MPN88). Sequence comparison within and among Pinctada species pointed to intra- and interspecies variations relevant to polymorphism and to evolutionary distance, respectively. In addition, a novel shell matrix protein, linkine was identified. BLAST analysis of the peptide sequences obtained from the shell of P. margaritifera against the EST database revealed the presence of additional proteins: two proteins similar to the Pif97 protein that was identified in the shell of P. fucata, a chitinase-like protein previously identified in Crassostrea gigas, two chitin-binding proteins, and two incomplete sequences of proteins unknown so far in mollusk shells. Combining proteomics and transcriptomics analysis we demonstrate that all these proteins, including linkine, are addressed to the shell. Retrieval of motif-forming sequences, such as chitin-binding, with functional annotation from several peptides nested in the shell could indicate protein involvement in shell patterning.

Evolution of nacre: biochemistry and proteomics of the shell organic matrix of the cephalopod Nautilus macromphalus

In mollusks, one of the most widely studied shell textures is nacre, the lustrous aragonitic layer that constitutes the internal components of the shells of several bivalves, a few gastropods,and one cephalopod: the nautilus. Nacre contains a minor organic fraction, which displays a wide range of functions in relation to the biomineralization process. Here, we have biochemically characterized the nacre matrix of the cephalopod Nautilus macromphalus. The acid-soluble matrix contains a mixture of polydisperse and discrete proteins and glycoproteins, which interact with the formation of calcite crystals. In addition, a few bind calcium ions. Furthermore, we have used a proteomic approach,which was applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Our data demonstrate that the insoluble and soluble matrices, although different in their bulk monosaccharide and amino acid compositions, contain numerous shared peptides. Strikingly, most of the obtained partial sequences are entirely new. A few only partly match with bivalvian nacre proteins.Our findings have implications for knowledge of the long-term evolution of molluskan nacre matrices.

Low molecular weight molecules of oyster nacre induce mineralization of the MC3T3-E1 cells

The nacre layer from the pearl oyster shell is considered as a promising osteoinductive biomaterial. Nacre contains one or more signal molecules capable of stimulating bone formation. The identity and the mode of action of these molecules on the osteoblast differentiation were analyzed. Water-soluble molecules from nacre were fractionated according to dialysis, solvent extraction, and reversed-phase HPLC. The activity of a fraction composed of low molecular weight molecules in the mineralization of the MC3T3-E1 extracellular matrix was investigated. Mineralization of the preosteoblast cells was monitored according to alizarin red staining, Raman spectroscopy, scanning electron microscopy, and quantitative RT-PCR. Molecules isolated from nacre, ranging from 50 to 235 Da, induced a red alizarin staining of the preosteoblasts extracellular matrix after 16 days of culture. Raman spectroscopy demonstrated the presence of hydroxyapatite (HA) in samples treated with these molecules. Scanning electron microscopy pictures showed at the surface of the treated cells the occurrence of clusters of spherical particles resembling to HA. The treatment of cells with nacre molecules accelerated expression of collagen I and increased the mRNA expression of Runx2 and osteopontin. This study indicated that the nacre molecules efficient in bone cell differentiation are certainly different from proteins, and could be useful for in vivo bone repair.

The effect of molecules in mother-of-pearl on the decrease in bone resorption through the inhibition of osteoclast cathepsin K

This study evaluates the effect of the mother-of-pearl (nacre) organic matrix on mammalian osteoclast activity and on cathepsin K protease. Rabbit osteoclasts were cultured on bovine cortical bone slices in the presence of water-soluble molecules extracted from nacre of the pearl oyster Pinctada margaritifera. Osteoclast resorption activity was determined by quantification of the resorption surface area on bovine bone slices. Papain and cathepsin K, B and L inhibition tests were performed in the presence of the nacre water-soluble extracts. The active crude extract was fractionated by dialysis and reversed-phase high-performance liquid chromatography before electrospray mass spectrometry analysis of inhibitory fractions. The water-soluble molecules extracted from nacre decreased bone resorption without jeopardizing osteoclast survival. The hydrolytic activity of cysteine proteinases was reduced when the enzymes were incubated with the nacre water-soluble molecules. Trending towards characterization of the molecules involved, it appears that cathepsin K inhibitors remain in different nacre water-soluble organic matrix subfractions, composed of low molecular weight molecules. Mollusk shell nacre contains molecules capable of reducing osteoclast bone resorption activity by inhibiting cathepsin K, giving a new facet of the bioactivity of nacre as bone biomaterial.

Proteomics analysis of the nacre soluble and insoluble proteins from the oyster Pinctada margaritifera

Shell nacre is laid upon an organic cell-free matrix, part of which, paradoxically, is water soluble and displays biological activities. Proteins in the native shell also constitute an insoluble network and offer a model for studying supramolecular organization as a means of self-ordering. Consequently, difficulties are encountered in extraction and purification strategies for protein characterization. In this work, water-soluble proteins and the insoluble conhiolin residue of the nacre of Pinctada margaritifera matrix were analyzed via a proteomics approach. Two sequences homologous to nacre matrix proteins of other Pinctada species were identified in the water-soluble extract. One of them is known as a fundamental component of the insoluble organic matrix of nacre. In the conchiolin, the insoluble residue, four homologs of Pinctada nacre matrix proteins were found. Two of them were the same as the molecules characterized in the water-soluble extract. Results established that soluble and insoluble proteins of the nacre organic matrix share constitutive material. Surprisingly, a peptide in the conchiolin residue was found homologous to a prismatic matrix protein of Pinctada fucata, suggesting that prismatic and nacre matrices may share common proteins. The insoluble properties of shell matrix proteins appear to arise from structural organization via multimerization. The oxidative activity, found in the water-soluble fraction of the nacre matrix, is proposed as a leading process in the transformation of transient soluble proteins into the insoluble network of conchiolin during nacre growth.

Heterogeneity of proteinase inhibitors in the water-soluble organic matrix from the oyster nacre

We extracted proteinase inhibitors from the nacre of the oyster Pinctada margaritifera with water. Mixing the nacre powder with water for 20 h led to a water-soluble fraction [0.24% (wt/wt) of nacre]. After dialysis of the water-soluble matrix through 6- to 8-kDa and 0.5-kDa membranes, the proteinase inhibitors were divided into low and high molecular weight fractions that contained inhibitors of papain, bovine cathepsin B, and human cathepsin L. We studied the heterogeneity of the inhibitors after separating the low molecular weight fraction according to charge and hydrophobicity. After multistep purification, mass spectrometry analysis revealed that a potent inhibitory fraction contained several molecules. This observation demonstrates the difficulties encountered in attempting to isolate individual metabolites from the complex mixture of molecules present in nacre matrix. Interestingly, the low molecular weight fraction contained specific inhibitors that could discern between cathepsin B and cathepsin L. The nacre organic inhibitors were active against several cysteine proteinases, yet they were more specific in relation to serine proteinases, because only proteinase K was inhibited. These results demonstrate, for the first time, the presence of active proteinase inhibitors in the mollusc shell, and it is possible that these inhibitors may play a role in either protection of proteins involved in shell formation or in defense against parasites, or both.

The in vitro osteoclastic degradation of nacre

Osteoclast activity was studied on nacre, the mother of pearl (MOP) in order to assess the plasticity of bone resorbing cells and their capacity to adapt to a biomineralized material with a different organic and mineral composition from that of its natural substrate, bone. Pure MOP, a natural biomineralized CaCO(3) material, was obtained from Pinctada oyster shell. When implanted in the living system, nacre has proven to be a sustainable bone grafting material although a limited surface degradation process. Osteoclast stem cells and mature osteoclasts were cultured on MOP substrate and osteoclast precursor cells were shown to differentiate into osteoclasts capable of resorbing nacre substrate. However, analysis of the organization of the cytoskeleton showed that both a sealing zone and a podosome structure were observed on the nacre substrate. Moreover, MOP resorption efficiency was consistently found to be lower than that of bone and appeared to be a limited process.

Identification of low molecular weight molecules as new components of the nacre organic matrix

Nacre of Pinctada margaritifera displays a number of interesting biological activities on bone, mainly concentrated in a water-soluble organic matrix representing 0.24% of the nacre weight. Dialysis of that matrix through 8 kDa and 1 kDa cut-off membranes showed that 60% of it is made of small molecules of molecular masses below 1 kDa. Reversed-phase high-performance liquid chromatography of the small molecule fractions and subsequent electrospray ionization mass spectrometric analysis of 19 fractions thereof indicated the presence of at least 110 different molecules, in the range 100 Da-700 Da. Evidence for aggregate-forming properties of the small molecules was given. Amino acid analysis revealed that most of the small molecules were not peptides and tandem mass spectrometric gas-phase fragmentations clearly indicated a structural relationship between several molecules. Intriguingly, differences of a single Dalton between mono-charged ions peaks were observed. Further, approximately 40 analytes could be arranged in a ladder-like manner with mass spaces of 57 Da. Some of the water-soluble peptide sequences obtained after MS/MS fragmentation revealed that the 57 Da shift corresponds to the repetition of glycine residues. Furthermore, the exchange of glycine against alanine explains the 14 Da shift observed between some peptides. These data show for the first time that small molecules, especially peptides, are prevalent components of nacre. The molecular species described in this report might have a functional role in nacre.

Identification of calconectin, a calcium-binding protein specifically expressed by the mantle of Pinctada margaritifera

Nacre or mother-of-pearl in the shell of Pinctada margaritifera is composed of 95-99% calcium carbonate and 1-5% organic matrix. In this study, we developed an original technique to characterize the genes differentially expressed in nacre-forming cells (NFC) by combining suppression subtractive hybridization (SSH), to establish a cDNA subtractive library, with rapid amplification of cDNA ends (RACE)-PCR. Seventy-two specific cDNA sequences have been obtained so far. These include a protein containing two EF-hand Ca2+-binding domains which was completely sequenced after amplification by RACE-PCR. Its specific expression as well as the specificity of the SSH method was confirmed by semi-quantitative RT-PCR on NFC and mantle cells.

Methods for obtaining neutral and acid oligosaccharides from flax pectins

Esterified acid soluble pectins from flax (Linun usitatissimum L.) were degraded either with HCl or pectin lyase. Centrifugation and 2-propanol precipitation led to the isolation of two low molecular weight polygalacturonates after acid hydrolysis of pectins. However, after pectin lyase digestion and purification by size-exclusion HPLC, (1)H NMR analyses indicated that acetylated hairy regions, large methylated and acetylated oligogalacturonides together with small unsubstituted oligogalacturonides were produced. Thus, in a few steps, a panel of substituted neutral and acidic oligosaccharides was produced from a raw plant material. Such oligosaccharides could be useful for further fractionations such as chemical saponification and enzymatic removal of neutral sugar chains from the hairy regions. The procedures used for pectin extraction, for degradation, and for the purification of fragments seem appropriate for large-scale production of biologically active oligosaccharides from flax.

Recovery of the oxidative activity of caged bovine haemoglobin after UV photolysis

Caging of bovine haemoglobin with increasing amounts of 1-(2-nitrophenyl)ethyl (NPE) and uncaging after a 366 nm irradiation was examined. Caged and photolysed conjugates were characterised by enzymatic assay of the ABTS oxidation, UV/Vis absorbance, and electrospray mass ionisation. Modification of haemoglobin with 50, 75, and 100 equivalents of 1-(2-nitrophenyl)diazoethane led to a progressive decrease of enzymatic activity. Photolysis at 366 nm during 5, 15, and 30 min induced the recovery of a part of the enzymatic activity. ESI analyses showed that a reversible binding of up to 6 NPE groups per alpha-chain and that the removal of most of the photolabile groups occurred rapidly after 5 min of illumination at 366 nm and reached near completion after 15 min. A variable alteration of haemoglobin after labelling could explain that the complete removal of NPE groups did not restore its full oxidative activity.

Rapid quantification of O-acetyl and O-methyl residues in pectin extracts

A rapid method for the determination of the degrees of methylation (DM) and acetylation (DA) of pectins was developed. The polymer substitution degree as determined after saponification at 80 degrees C with NaOD during 1H NMR analysis. Under alkaline conditions, the cleavage of O-acetyl and O-methyl linkages allows the detection and the integration of the H-4 signal from galacturonic acid residues in the newly unesterified pectins. So, after a 10-min NMR recording, sodium acetate and sodium methanolate can be easily quantified relative to the clearly identified H-4 signal in galacturonic acid residues. Protons signals from pectin neutral sugars do not interfere with H-4. During the analysis, a limited (<3%) methanol evaporation leading to a weak reduced signal from the methanolate protons was observed. The proposed method allows in few minutes an accurate simultaneous quantification of DM and DA from few mg of pectin extracts, without the need of external standards.

Uptake of plasmid/glycosylated polymer complexes and gene transfer efficiency in differentiated airway epithelial cells

BACKGROUND

We have studied gene transfer efficiency of glycosylated polylysines and glycosylated polyethylenimines as vectors in immortalized differentiated airway gland serous cells and primary cultures of human airway surface epithelial cells.

METHODS AND RESULTS

In both cell types, lactosylated PEI was more efficient for gene transfer than unsubstituted PEI and lactosylated polylysine which requires the presence of endosomolytic agents. However, for all the vectors tested, gene transfer efficiency was lower in differentiated cells as compared with poorly differentiated cells. The presence of membrane lectins, i.e. cell surface sugar-specific receptors, was evaluated using fluorescein-conjugated neoglycoproteins and microscopy or flow cytometry. In differentiated airway surface epithelial cells, membrane lectins were not expressed and plasmid DNA/fluorescein-conjugated glycosylated polymer complexes were not incorporated. This accounted in part for the lack of gene transfer efficiency in these cells. In contrast, in differentiated airway gland serous cells, expression of lectins and their endocytotic properties appeared to be similar to that observed in undifferentiated cells, and plasmid DNA/fluorescein-conjugated glycosylated polymer complexes were incorporated in similar amounts by cells in both differentiated states

CONCLUSIONS

Glycosylated PEI appears to be a promising gene delivery system since it is more efficient than the sugar-free polymer and does not require endosomolytic agents. However, in differentiated airway gland serous cells, a low gene transfer efficiency was observed that could not be attributed to low expression of membrane lectins or low uptake of glycosylated complexes. An impaired intracellular trafficking of glycosylated complexes in differentiated airway gland serous cells is suggested.

Uptake of dimannoside clusters and oligomannosides by human dendritic cells

Knowing that human blood monocyte-derived dendritic cells express cell-surface mannose-specific lectins, we prepared various mannoses containing glycoconjugates with the aim of developing highly specific synthetic carriers of oligonucleotides and genes. Conjugates were prepared from oligosaccharides obtained by hydrazinolysis of Saccharomyces cerevisiae invertase glycopeptides. The reducing saccharides were converted into glycosynthons, i.e., into glyco-amino acids. Fluorescein derivatives were obtained by coupling the free carboxyl group of oligosaccharyl-pyroglutamate to the alpha-amino group of epsilon-fluoresceinyl-thiocarbamyl lysine methyl ester. It has been shown by others that glycosylated linear oligolysines containing up to six alpha-D-mannopyranosylphenylthiocarbamyl units have a high affinity for the human mannose receptor. In order to obtain fully biodegradable clusters and to improve both the specificity and the selectivity, disaccharides transformed into glycosynthons were coupled to pentalysine carriers (Lys5-Ala-Cys-NH2). Glycosylated pentalysyl cysteine conjugates were made fluorescent upon substitution of the cysteine thiol group with fluorescein iodoacetamide. As shown by flow cytofluorimetry, both the dimannoside clusters and yeast oligomannosides were very efficiently taken up by DC, conversely lactoside clusters were not.

Soluble proteins of the nacre of the giant oyster Pinctada maxima and of the abalone Haliotis tuberculata: extraction and partial analysis of nacre proteins

Several proteins from nacre of the oyster Pinctada maxima and the abalone Haliotis tuberculata were extracted and partly characterized. Proteins dispersed in aragonite were solubilized during demineralization with acetic acid whereas proteins adsorbed on conchiolin were extracted with sodium dodecyl sulfate and beta-mercaptoethanol. The matrix of Pinctada maxima nacre is composed of one main protein with an apparent molecular weight of 20 kDa (p20). This protein was found in the acetic acid soluble fraction of nacre, as well as in the Laemmli-solubilized extract of conchiolin. In addition, the p20 solubilized with acetic acid can form oligomers made of 6 monomers linked together by disulfide bridges. The first N-terminal 21 amino acids of p20 were determined and no homology with known proteins was found. In Haliotis tuberculata nacre, 5 main proteins were solubilized during demineralization and 3 glycoproteins were detected. Stains-all and Alcian blue staining revealed polyanionic proteins in the extracts isolated from Pinctada maxima and Haliotis tuberculata nacre.

Characterization and quantification of chitosan extracted from nacre of the abalone Haliotis tuberculata and the oyster Pinctada maxima

This study was performed to characterize and quantify chitosan by simple physicochemical methods (infrared spectroscopy and potentiometric measurements). These procedures were validated with well-characterized chitosan before being used to investigate chitosan in nacre of the abalone Haliotis tuberculata and of the giant oyster Pinctada maxima. Potentiometric study revealed a chitosan extract from the nacre of H. tuberculata with a degree of deacetylation of around 88% and an intrinsic pK of 6.5. According to infrared and potentiometric data, a low yield (eta) of extraction was calculated (eta = 0.064%). For experiments performed on the nacre of P. maxima, and in spite of more stringent deacetylation conditions, results suggested that a chitin-protein complex (eta = 0.053%) was isolated rather than chitosan.

Cloning and sequencing of the central region of the flagellin gene from the Gram-positive bacterium Clostridium tyrobutyricum ATCC 25755

The purpose of this study was to sequence the central part of the coding region of the Clostridium tyrobutyricum fiagellin gene to improve the immunoenzymatic counting of cells after milk filtration. The coding region was amplified by PCR, and the amplified products were cloned. A DNA sequence analysis of positive clones gave us 1,131 nucleotides with a partial calculated flagellin molecular mass of 40,143 Da. The flagellar filament protein sequence exhibited high levels of homology to sequences of flagellin protein from other bacteria in both N- and C-terminal parts, but little homology in the central domain. A PCR-restriction fragment length polymorphism analysis of amplified C. tyrobutyricum flagellin gene products confirmed the variability of the central domain. The flagellin mRNA was determined to be 1.1 kb in size, which suggests a monocistronic mRNA. Furthermore, the deduced protein flagellin contains eleven potential N-glycosylation sites and one sequence rich in serine, which could be modified by O-glycosylation.

Evidence for an heterogeneous glycosylation of the Clostridium tyrobutyricum ATCC 25755 flagellin

Glycosylation analysis of the flagellin from the Gram-positive species Clostridium tyrobutyricum has been supplemented. Amino acid analysis of the glycopeptides obtained after pronase digestion of flagellin indicated that O-glycosylation which was previously demonstrated after nonreductive beta-elimination, probably occurred via the hydroxyl group of serine. Otherwise, beta-elimination partly deglycosylated flagellin. After this treatment carbohydrates were still linked to protein as shown by a digoxigenin-hydrazide labelling. Therefore, in addition to linkages via serine, alkaline resistant linkages exist on the flagellin and some glycans may be linked to the protein core via the amide nitrogen of asparagine or via the hydroxyl group of tyrosine. Furthermore, according to an immunological analysis, glycans attached to flagellin via alkaline sensitive linkages may be different from those attached via alkaline resistant linkages.

Partial analysis of the flagellar antigenic determinant recognized by a monoclonal antibody to Clostridium tyrobutyricum

In order to count Clostridium tyrobutyricum spores in milk after membrane filtration, murine 21E7-B12 monoclonal antibody was produced. Elution of the monoclonal antibody from this antigen, the flagellar filament protein, by carbohydrate ligands was used to study the epitope structure. A competitive elution of an anti-dextran monoclonal antibody by carbohydrate ligands served as a control in order to validate the immunological tool applied to flagellin epitope study. The carbohydrate moiety of flagellin contained D-glucose and N-acetyl-glucosamine in a molar ration of 11:1 as determined by gas-liquid chromatography and 2 low-abundancy unidentified compounds. In ELISA, D-glucose and N-acetyl-glucosamine did not dissociate the antibody-flagellin complex contrary to maltose, maltotriose, maltotetraose and maltopentaose. The efficiency of elution increased from the dimer to the pentamer and became nil for maltohexaose and maltoheptaose. The fact that the hexamer and heptamer could not react with the 21E7-B12 monoclonal antibody could be explained by a drastic conformational change. The over-all stretched maltopentaose switch to a helical-shaped maltoheptaose which could not fit the 21E7-B12 monoclonal antibody antigen-combining site. Thus, flagellin epitope may contain alpha (1-->4) linked glucose residues plus either N-actyl-glucosamine or an unidentified compound that maintain it in an extended shape.

Biochemical and immunological analyses of the flagellin of Clostridium tyrobutyricum ATCC 25755

The monoclonal antibody 21E7-B12 (IgG3) can be used in a direct method of Clostridium tyrobutyricum detection based on an immunoenzymatic assay. Immunoelectron microscopy demonstrated that the 21E7-B12 antibody recognized the surface-exposed epitopes on the flagellar filaments of C. tyrobutyricum. After flagellar extraction, the purified flagellin showed an apparent molecular mass of 46 kDa with an isoelectric point of 3.6. Sugar staining, mild periodate oxidation and beta-elimination experiments showed that the flagellin was glycosylated and that the 21E7-B12 epitope was located in the sugar moiety. Amino acid composition showed that the flagellar filament protein contained a high percentage of serine and threonine, while proline was absent. The first 23 residues of the N-terminal were determined and sequence homology with other flagellins was found.